Abstract 9793: Systematic Rhythm Analysis of Automated External Defibrillators Reveals a High Proportion of Shockable Rhythm
Introduction: There is little information about systematic downloading and rhythm analyses of data retrieved from Automated External Defibrillators (AEDs) that have been deployed by untrained laypersons during out-of-hospital cardiac arrest (OHCA).
Hypothesis: We assessed the hypothesis that a higher proportion of shockable rhythm would be detected with AEDs when compared to Emergency Medical Services (EMS) rhythm analyses.
Methods: In a 20-month study, we collected data on OHCAs in the Capital Region of Denmark (population 1.7 million) where an AED was deployed prior to EMS arrival. The AEDs were brought to the emergency medical dispatch centre for data downloading and rhythm analysis. EMS rhythm analyses were obtained from the Danish Cardiac Arrest Register between 2001 and 2010. A sample of 120 cardiac arrests would allow us to detect a difference in shockable rhythms between initial EMS and AED rhythm analyses from 25% to 50% with a statistical power of at least 80% at the 5% significance level.
Results: A total of 121 AEDs were deployed, of which 91 cases were OHCA with presumed cardiac origin. The prevalence of initial shockable rhythm was 55.0% (95% CI [44.7-64.8%]). This was significantly greater than the corresponding proportion recorded by the EMS (27.6%, 95% CI [27.0-28.3%], p<0.0001). Shockable arrests were significantly more likely to be witnessed (92% vs. 34%, p<0.0001), occur during exercise (28% vs. 2%, p=0.001) and have a higher bystander CPR rate (98% vs. 65%, p=0.04) (Table 1). More patients with initial shockable rhythm achieved return of spontaneous circulation upon hospital arrival (88% vs. 7%, p<0.0001) and had higher 30-day survival rate (72% vs. 5%, p<0.0001). There was no difference in EMS response time between shockable and non-shockable arrests (median, 5.7 min vs. 6.7 min, p=0.22).
Conclusions: In conclusion, AEDs used by laypersons revealed a higher proportion of shockable rhythms compared to the EMS rhythm analyses.
- Cardiac arrest
- Automated external defibrillator (AED)
- Basic life support
- Cardiopulmonary resuscitation
Author Disclosures: M.B. Hansen: None. F.K. Lippert: None. L.S. Rasmussen: None. A.M. Nielsen: None.
- © 2014 by American Heart Association, Inc.